Electronic devices of various kinds are well known. Such electronic devices can electronic signals between circuits or over devices to pass information or trigger operation of various elements. For example, modern automobiles include a wide variety of electronically controlled devices disposed throughout the vehicle. Such devices can send signals between each other and/or to the vehicle's central computer for processing. To send such signals, switches transmit or block such signals to facilitate orderly communication. For example, a transmission gate or analog switch can control passing of an incoming signal on to other devices or circuit elements. In one state, the transmission gate blocks the signal, and in another state, the transmission gate passes a signal at its input to its output.
One known approach to handling this application is illustrated in FIG. 1, which illustrates a circuit 10 including a PMOS transistor 12 connected to an NMOS transistor 14. The circuit 10 is controlled by a voltage to the respective gates of the two transistors 12 and 14. A first voltage opens both transistors 12 and 14 to allow a signal at the input to pass to the output, and a second voltage closes both transistors 12 and 14 to block any signals from passing between the input and output.
Such a standard transmission gate has various disadvantages. For example, the input signal can be clamped or cut off when the input signal is too high because the transistors 12 and 14 cannot physically handle such a signal unless specifically designed and built to do so. Also, back-feed signals can travel from the input to the output due to a parasitic diode effect on the PMOS transistor of the gate. Such a transmission gate can also fail to pass an input signal without significant signal degradation or change when the input signal varies over a wide range or when power to control the transmission gate is in flux.